German Pat. No. 2,806,525 describes a device for extracting the rolls from rolling mill frames and for aligning of the top or top edge of the lower working roll with reference to the roll gap or plane. This prior art device is equipped with a roll changing cart on which are arranged several shim plates of distinct height.
By way of a drive unit the shim plates can be brought beneath the holding elements for the respective rolls. For such positioning, the shim plates are arranged on a shift frame which is movably guided on a track arranged on the roll change cart and which is connected to the drive unit. The drive unit includes at least one spindle which is journaled in the roll change cart and also includes a motor and a transmission for imparting motive power to the spindle.
The prior art apparatus further includes lift elements for supporting the holding elements, and these lift elements are arranged on each of the two sides of the shift frame in the roll change cart.
The prior art apparatus employs shim plates of various thicknesses, but does not allow for a step-less continuous alignment to alleviate problems of wear of the roll.
Step-less adjustable devices are known, and the maximum distance which can be traversed to adjust the respective height of the holding elements is controlled by way of wedges. However, this system does not permit displacement in the direction of the axes of the rolls. Due to the unnecessarily small wedge angle, the wedges, furthermore, need to be rather long, to avoid the possibility of jamming and like problems.
Accordingly, the prior art systems are undesirably bulky, are not very economical, and are prone to require a large amount of maintenance and space.